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EN
This article compares the deflections of reinforced concrete beams with reinforcement degrees of ρ=1.02% and ρ=1.78%, made of lightweight aggregates, i.e. Certyd, LECA, and an innovative aggregate made of plastic waste. Two methods were used for the comparison experimental and computational. The computational part was performed using the finite element method (FEM) in ANSYS software. The adopted properties of lightweight concrete were sourced from the authors’ experimental research. A comparison of deflections based on the data obtained using both methods showed that, for reinforced concrete elements with a degree of reinforcement of ρ=1.02%, the smallest difference was obtained in the case of beams made of plastic waste concrete, while the highest difference was obtained for beams made of concrete with lightweight expanded clay aggregate. In the case of reinforced concrete elements with a degree of reinforcement ρ=1.78%, the lowest differences were obtained for beams made of lightweight aggregates, i.e. Certyd and LECA. For those beams that used plastic waste aggregate, the difference was 20%, compared to experimental tests.
PL
W artykule porównano ugięcia belek żelbetowych o stopniu zbrojenia ρ=1,02% i ρ=1,78%, wykonanych z lekkich kruszyw, tj. Certyd, LECA i innowacyjnego kruszywa wykonanego z odpadów tworzyw sztucznych. Do porównania wykorzystano dwie metody: eksperymentalną i obliczeniową. Część obliczeniowa została wykonana przy użyciu metody elementów skończonych (MES) w oprogramowaniu ANSYS. Przyjęte właściwości betonów lekkich pochodziły z badań eksperymentalnych autorów. Porównanie ugięć na podstawie danych uzyskanych za pomocą obu metod wykazało, że dla elementów żelbetowych o stopniu zbrojenia ρ=1,02% najmniejszą różnicę uzyskano w przypadku belek wykonanych z betonu z odpadów tworzyw sztucznych, natomiast największą różnicę uzyskano dla belek wykonanych z betonu z lekkim kruszywem keramzytowym. W przypadku elementów żelbetowych o stopniu zbrojenia ρ=1.78% najmniejsze różnice uzyskano dla belek wykonanych z kruszyw lekkich, tj. Certyd i LECA. W przypadku belek, w których zastosowano kruszywo z odpadów tworzyw sztucznych, różnica wyniosła 20% w porównaniu z badaniami eksperymentalnymi.
EN
Electrical contacts are used in general electrical applications such as circuit breakers, switches, relays, connectors, etc. Repeated separations of the parts (anode and cathode) of these contacts under input power can damage their contact materials. The objective of this work is to study the influence of the input electric power (100 W and 256 W) and the contact sizes (hemispherical contacts with diameters 𝐷 = 5 mm and 𝐷 = 8 mm) on the variation of the arc energy and the damage of the contact surfaces by oxidization or by erosion. These parameters are decisive for selecting the best arcresistant contact sample. Experimental results, SEM, and EDX analysis show that high input power leads to more degradation of contact surfaces. Also, the smaller and the larger contact diameters generate similar arcing energies with similar erosion sizes and oxidation rates, but the contact with a small diameter has a higher lifetime (1215 operations) and oxidizes less quickly than the one with a large diameter that has a lower lifetime (374 operations). Experimental and numerical analyses demonstrat that arc mobility is one of several factors influencing the change in contact lifetime.
EN
The aim of this study was to evaluate the abrasive wear of the sliding screw-rod joint used in growth guidance system (GGS) stabilizers, allowing for the translation of the screw along the rod during the spinal growth process in a standard and modified system. Methods: The study used single kinematic screw-rod pairs made of titanium alloy Ti6Al4V. Mechanical tests (cyclic loads) simulated the stabilizer’s operation under conditions similar to actual use. A microscopic evaluation was conducted, analyzing abrasive wear based on measured abrasion areas. Numerical simulations were performed for the standard joint system and for a structural change (an additional insert to increase contact area between the rod and sliding screw cap). Results: The study evaluated the abrasive wear of the mating elements of the stabilizer. Mechanical tests showed an increase in the force observed (11.74 ± 2.52 N) with the increasing number of load cycles. Microscopic evaluation showed abrasion of the caps and rods in two areas (upper and lower). Numerical simulations indicated the highest stresses in the standard system were on the mating elements, i.e., the rod and the cap (15.6 MPa). In the modified joint, stress distribution differed, concentrating on the surface of the insert and the rod, with maximum values of 6.0 MPa (PE insert) and 12.4 MPa (PEEK insert). Conclusions: Comparing the stress distributions obtained in the numerical simulations and the abrasive wear effects produced in the mechanical tests, a similar mechanism was observed (the destruction of the top layer of the mating elements of the stabilizer).
EN
The article deals with the design of the stacking sequence of layers in composite plate element in order to create the desired behaviour in the postcritical range. Tested plates were made of carbon fiber reinforced polymer (CFRP) laminate with different layer arrangement. As the type of load, the axial compression was assumed. The configurations have been choosen specifically to investigate the influence of Extension-Twisting and Extension-Bending coupled designs under axial load. To analyse the influence of layer arrangement on the posbuckling behaviour the parametric study was performed. Matlab software and a script developed by the author were used to calculate the components of ABD matrix. Additionally, the experimental validation was carried out together with numerical analysis.
EN
The paper presents the results of research on fragments of thin-walled coverings made of aluminum alloy. The exmined structures were subjected to shear stresses leading to post-critical deformations. Three types of elements were analyzed: an element without stiffeners (the referencial one), an element with three stiffening ribs and an element with five stiffening ribs. The results of numerical analyzes and static experimental research were presented. Althought this kind of solutions is commonly used in various aircraft structures, the publications about it are usually hard to rich. The research concerning ribbed stiffeners are usually performed inside laboratories of aerospace concerns and their results are not published in the open sources. The general direction of analyses of this solution is indicated in presented study.
EN
This paper presents a study of compressed thin-walled composite columns with an open cross-section. The tested specimens with a top-hat cross-section were made of CFRP material. Two arrangements of composite layers [0/-45/45/90]s and [90/0/90/0]s were compared. The paper focuses on the buckling phenomenon and the determination of the critical loads of the structure. It includes both numerical analyses using the finite element method (FEM) and validation on real specimens made using the autoclave technique. A comparison is made between the results obtained by both methods. The critical forces of the real specimens were determined using the P-wc3 approximation method. Both the evaluation of the buckling shape and the values of the critical forces showed a significant correlation between the experimental and numerical tests. This paper also compares the tested lay-ups.
EN
This paper deals with the experimental and numerical analysis of three-point bending phenomenon on beam composite profiles. Flat rectangular test specimens made of carbon–epoxy composite, characterised by symmetric [0/90/0/90]s laminate ply lay-up, were used in this study. Experimental testing was carried out with a COMETECH universal testing machine, using special three-point bending heads. In addition, macroscopic evaluation was performed experimentally using a KEYENCE Digital Microscope with a mobile head recording real-time images. Parallel to the experimental studies, numerical simulations were performed using the finite element method in ABAQUS software. The application of the above-mentioned interdisciplinary research techniques allowed for a thorough analysis of the phenomenon of failure of the composite material subjected to bending. The obtained research results provided a better understanding of the failure mechanism of the composite material.
EN
The study continues the advanced analytical modelling of the linear elasticity and viscoelasticity of thermosets and unidirectional glass fibre-reinforced thermoset-matrix (UFRT) composites. The thermosets are isotropic materials with viscoelastic shear strains and elastic bulk strains, and the fibres are isotropic and elastic. The modified homogenization theory for UFRT composites, based on the selected tasks of the linear theory of elasticity, is developed. The modifications include a volumetrically equivalent cylindrical representative volume cell, solutions determined for an isotropic fibre based on the solutions for a monotropic (transversely isotropic) fibre, and certain modifications in the third task of the theory of elasticity. The viscoelastic constants of the thermoset are derived analytically and validated by fitting of the simulation and experimental shear strains on a logarithmic time scale in the unidirectional tension creep test. The viscoelastic constants of the UFRT composite are derived analytically and validated by fitting of the storage compliances corresponding to the new viscoelastic model and one obtained from the viscoelastic-elastic correspondence principle. The tension creep experiment is performed on the selected structural unsaturated polyester resin. Identification and validation are carried out for that thermoset and the corresponding UFRT composite with long E-glass fibres. All the modelling hypotheses are confirmed.
EN
Dynamic tests with different load ratios and frequencies provide designers with the necessary information to evaluate the longevity of different structures as well as minimize weight due to a possibly smaller factor of safety. The influence of loading frequency on the fatigue behaviour of an aluminium composite material (ACP) with an aramid honeycomb core was studied. The mechanical behaviour was assessed by three-point static bending tests, followed by cyclic flexural fatigue tests employing the fabricated sandwich samples, with loading frequencies of 5, 7.5 and 10 Hz. The experimental results were presented on a single graph in order to highlight the different behaviours for the adopted frequencies. Indeed, the tests allowed the authors to determine the different cycle number values necessary to achieve resistance losses of 10 and 25%, respectively. The experiments were carried out for the same loading level of 80% of the maximum force, which is taken as equal to the elastic limit in order to avoid the field of plastic deformations.
EN
The article features the results of computer and experimental research on operational issues in the aspect of safety in relation to a freight wagon derailment on a railway track. It presents the knowledge regarding the methods of assessing the operational safety of rail vehicles on railroad tracks for the purpose of comparative analysis. The theoretical analyses were performed based on several methods that assess the safety of their derailments, qualifying for operational reliability, comparing them with the results obtained from experimental research. For the purpose of the research, a computer model of rail vehicle- railway track was created. It took into consideration dynamic parameters of elements used in the real track and rail vehicle. The results obtained from theoretical analyses were validated with experimental tests carried out on real objects (freight vehicle - test track, freight wagon - test rig). As part of the research, new test track geometry for testing rail vehicles was proposed. The results obtained in this way allowed estimating the conditions threatening the operation of a freight vehicle while running on the test rail infrastructure with different assessment criteria and to compare them.
PL
W pracy pokazano rezultaty badań komputerowych i eksperymentalnych dotyczących zagadnień eksploatacji w aspekcie bezpieczeństwa w odniesieniu do wykolejenia wagonu towarowego na torze kolejowym. Przybliżono w nim stan wiedzy dotyczącej metod oceny bezpieczeństwa eksploatacji pojazdówa) szynowych na kolejowych liniach szynowych, w celu ich analizy porównawczej. W pracy wykonano analizy teoretyczne bazując na kilku metodach, które oceniają bezpieczeństwo ich wykolejenia, kwalifikujące się do niezawodność eksploatacyjnej, porównując je z wynikami otrzymanymi z badań eksperymentalnych. Na potrzeby przeprowadzanych badań powstał komputerowy model pojazd szynowy - tor kolejowy. Uwzględniał on parametry dynamiczne elementów zastosowanych w rzeczywistym torze oraz pojeździe szynowym. Otrzymane z teoretycznych analiz wyniki zwalidowano testami eksperymentalnymi wykonanymi na rzeczywistych obiektach (pojazd towarowy - tor testowy, wagon towarowy - stanowisko badawcze). W ramach badań zaproponowano nową geometrię toru testowego do badań pojazdów szynowych. Uzyskane wyniki pozwoliły określić stan zagrożenia eksploatacji wagonu towarowego podczas jazdy po testowej infrastrukturze szynowej przy różnych kryteriach oceny oraz je porównać.
PL
Proces urabiania, zwłaszcza skał trudno urabialnych, wysięgnikowymi kombajnami chodnikowymi jest źródłem silnych obciążeń dynamicznych, nie tylko napędu głowic urabiających, ale również mechanizmów wychylania wysięgnika, na którego końcu głowice te są rozmieszczone. Zapewnienie odpowiednich proporcji pomiędzy wartościami parametrów siłowych mechanizmów wychylania wysięgnika oraz mocą napędu głowic urabiających i masą kombajnu ma kluczowe znaczenie z punktu widzenia skuteczności i efektywności urabiania czoła przodku drążonego wyrobiska korytarzowego w kopalniach podziemnych lub tuneli. W artykule przedstawiono wybrane wyniki badań doświadczalnych kombajnu chodnikowego R–130 (prod. Famur S.A.) w warunkach półprzemysłowych. Na podstawie charakterystyk dynamicznych zarejestrowanych podczas urabiania powierzchni bloku cementowo-piaskowego określone zostały relacje pomiędzy obciążeniem napędu głowic urabiających oraz mechanizmów wychylania wysięgnika. Zbadano wpływ technologii urabiania (rodzaju skrawu wykonywanego podczas przemieszczania głowic urabiających w ruchu roboczym) przy różnych skojarzeniach wartości parametrów procesu urabiania na obciążenie napędów kombajnu chodnikowego odpowiedzialnych za realizację tego procesu.
EN
The mining process, especially of hard rocks, using boom–type roadheaders is the source of strong dynamic loads not only for the drive of cutting heads, but also for boom swinging mechanisms, at the end of which these cutting heads are arranged. Ensuring appropriate proportions between the values of the force parameters of the boom swinging mechanisms and the power of cutting heads drive and the weight of the roadheader is of key importance from the point of view of efficiency and effectiveness of mining the heading face of the drilled roadways in the underground mine or tunnels. The article presents selected results of experimental investigations of the R–130 roadheader (manufactured by Famur S.A.) in laboratory conditions. On the basis of dynamic characteristics recorded during cutting of the cement-sand block surface, the relations between the load of the cutting heads drive and boom swinging mechanisms were determined. The influence of cutting technology (the type of cut performed during moving of cutting heads in a work movement) was examined with different associations of the values of cutting process parameters for the load of the roadheader’s drives responsible for this process.
EN
The experimental results of the prototype device for soil application of dewatered digestate, consisting of a modernized manure spreader and aggregated disc harrow, are presented. The main purpose of the tests were stress measurements in the harrow's frame structure and the hitch attached to the manure spreader's chassis. The results of measurements were found to be very consistent in real conditions with the results of strength analyzes carried out on the computational model. The work was carried out at the Industrial Institute of Agricultural Engineering in Poznań as part of the BIOSTRATEG 1/269056/NCBR/2015 project co-financed by the National Center for Research and Development under the Biostrateg program.
PL
Przedstawiono wyniki badań eksperymentalnych prototypu urządzenia do doglebowej aplikacji odwodnionego pofermentu, składającego się ze zmodernizowanego rozrzutnika obornika i zagregowanej z nim brony talerzowej. Głównym celem badań były pomiary naprężeń w konstrukcji nośnej brony i zaczepie zamocowanym do podwozia rozrzutnika. Stwierdzono dużą zgodność wyników pomiarów w warunkach rzeczywistych z wynikami analiz wytrzymałościowych przeprowadzonych na modelu obliczeniowym. Prace przeprowadzono w Przemysłowym Instytucie Maszyn Rolniczych w Poznaniu w ramach projektu BIOSTRATEG 1/269056/NCBR/2015 dofinansowanego przez NCBR w ramach programu Biostrateg.
EN
This paper contains an overview and analysis of semi-rigid joints in various types of construction. The behaviour of these joints is compared with the behaviour of joints in light wood-frame structures. The results of experimental tests of joints in light wood-frame structures are presented. In the experiments, displacements were recorded to calculate the bearing of elements in the joints as well as the rotation of the loaded element relative to the supporting element in the joint. A simple numerical model describing the semi-rigid behaviour of the joint is presented.
PL
W artykule omówiono istotne źródła hałasu w pojazdach samochodowych w odniesieniu do bezpieczeństwa w ruchu drogowym. Praca zawiera wyniki badań i analiz poziomu hałasu w wybranych miejscach w Jeleniej Górze. W opracowaniu wskazano wpływ poziomu hałasu na bezpieczeństwo.
EN
The article discusses important sources of noise in automotive vehicles in relation to road safety. The work contains the results of research and analysis of noise levels at selected locations in Jelenia Góra. The study indicates the impact of noise level on safety.
PL
Na strzelnicy firmy EMJOT przeprowadzono rejestrację procesu wystrzelenia z pistoletu maszynowego Glauberyt ogniem seryjnym czterech pocisków. Do badań empirycznych użyto amunicji 9x19 mm FMJ Luger (Parabellum) produkcji czeskiej z 2017 r. Strzały zostały oddane przez antyterrorystę. Ich rejestrację przeprowadzono z zastosowaniem szybkiej kamery cyfrowej Phantom v.9.1 wraz z niezbędnym oprzyrządowaniem. Na podstawie zarejestrowanego obrazu określono początkowe kinematyczne parametry lotu każdego z pocisków. Korzystając z zasad mechaniki lotu, opracowano model balistyczny pocisku, a na jego podstawie zredagowano program symulacyjny. Zweryfikowano wyniki lotu uzyskane w przestrzeni wirtualnej, porównując je z wynikami badań doświadczalnych. Po dopracowaniu modelu teoretycznego przeprowadzono estymację lotu czterech pocisków wystrzeliwanych ogniem seryjnym z pistoletu maszynowego Glauberyt do tarczy znajdującej się w odległości 25 m. W artykule przedstawiono reprezentatywny przykład wystrzeliwania ogniem seryjnym czterech pocisków. W badaniach wykonano 50 takich strzelań.
EN
At the EMJOT firing range, the process of firing the Glauberite machine gun was recorded with serial fire of four bullets. 9x19 mm FMJ Parabellum Luger Czech production from 2017 was used for empirical research. The shots were given by an anti-terrorist. Their registration was carried out using the high-speed Phantom v.9.1 digital camera, together with the necessary equipment. Based on the recorded image, the initial kinematic flight parameters of each of the missiles were determined. Using the principles of flight mechanics, a ballistic model of the projectile was developed, and on its basis a simulation program was prepared. Flight results obtained in the virtual space were verified by comparing them with the results of experimental tests. After finetuning the theoretical model, four flight bullets from the Glauberite machine pistol were estimated to be placed at the distance of 30 m. The article presents a representative example of serial firing of four missiles. Fifty such shots were made in the tests.
EN
The article presents the analysis, project, and experimental examination of an original rigid riser for Coil Tubing Pipes. The principle of riser operation is based on the use of friction forces. The research included the FEM analysis of the designed riser, calculations of the required bolt tensions, and checking the effect of the clamping force on stress distribution in the pipeline. The results of computer simulation were verified on a specially designed test rig. The described riser design was implemented on the LOTOS Petrobaltic platform, thus eliminating the need for purchase and installation of expensive elastic risers.
17
Content available remote Effect of Blades Settings on Rotor Dynamics
EN
In the paper, experimental and numerical studies of dynamics of a rotor composed of a rigid hub and three laminated blades with an embedded active piezoelectric actuators are discussed. The rotor is excited by periodic torque imposed to the hub. The dynamic response for various preset angles of the blades has been tested experimentally on the basis of signals recorded from strain gauges. The experimental results have been compared with a numerical finite element model developed in Abaqus software. The eigenvalue problem has been solved, and the natural frequencies and corresponding modes have been compared with experimental tests.
PL
W artykule omówiono konstrukcje oraz charakterystyki eksploatacyjne współczesnych termoelektrycznych schładzaczy oraz podgrzewaczy napojów, zwłaszcza charakterystyki dynamiczne. Przedstawiono wyniki badań porównawczych, pokazujących wpływ warunków wymiany ciepła między puszką lub butelką a pojemnikiem schładzacza na szybkość schładzania napoju. Rozmieszczenie wody w hermetyzowanej szczelinie między butelką z napojem a pojemnikiem schładzacza pozwala na istotne polepszenie dynamicznych charakterystyk urządzenia. Przykładowo, czas schładzania puszki z napojem od 25°C do 10°C w badanym schładzaczu skraca się z 67 do 50 minut.
EN
The article describes the constructive and operational characteristics of modern thermoelectric coolers and heaters of beverages, in particular, its dynamic characteristics. The results of comparative tests show the influence of the heat exchange conditions between the jar (bottle) and the cooler’s container on the cooling rate of the beverage. The distribution of water in the hermetic gap between the beverage bottle and the cooler container allows significant improvement of the dynamic characteristics of the device. For example, the cooling time of a beverage can from 25°C to 10°C in the tested cooler is shortened from 67 to 50 minutes.
EN
The paper is devoted to the experimental and theoretical analysis of wheelset elastic properties on the railway vehicle-track interaction. Results of experimental measurements of stiffness components of wheelsets obtained by a new measurement method are shown. Some types of wheelsets are considered with different wheel-disk design. For the theoretical analysis of bending and torsional flexibility of the wheel and wheelset are used. To numerical modeling of the considered wheels and wheelsets models the Finite Element Method (FEM) are applied. Simulation of dynamic interaction between a railway bogie and a curved sector of track in the rigid multibody systems method (VI-Rail software) is modeled. Exemplary simulations results obtained from the bogie-track system model using flexible and rigid model of the wheel and wheelset are presented.
EN
This article presents works associated with the design, numerical analyses and experimental tests of an energyabsorbing mat designed for increasing the safety of the soldiers inside military vehicles, especially their legs. One of the most important branches of engineering interests is high technologies accompanying the safety of soldiers. Energy absorbing mats are one of an additional equipment of a military vehicle, which is directly targeted to increase leg safety during explosion of IED (Improvised Explosive Device) under vehicle. The presented invention allows protection legs of the crew’s feet resting on the floor of the vehicle during explosion of a mine or IED. In most solutions, crewmembers’ foot rests directly on the floor, causing serious injuries. The value of the load on the metatarsus and tibia is closely related to the overall vehicle structure, which generally has limitations in the use of available external and internal protection solutions. Energy absorbing mats are a universal solution because they are adaptable to any type of vehicle. Their role is particularly important in flat-bottomed armoured vehicles. The article will show the results of the analysis showing how the mat works. Experimental results will be compared with the results of numerical analysis. The analysis is conducted using the LS-DYNA explicit code.
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